Not me, but it ought to work quite ok. You can create a profile for it that is managed separately from the one you have for the built-in screen. You'll need an appropriate adapter cable to suit the monitor input (e.g. dual DVI or perhaps displayport). If your MBP is too old then its graphics card may not cope with the high resolution of the 30" monitor.

If you intend to use the two screens to show different stuff at the same time then be aware that Lr and perhaps Ps can be a bit sloppy with updating the second screen. I tried it recently and I had enough problems to make me decide to use just a single screen and get speedy response rather than use two screens and get slow or no response on the second one. I'm talking about response to my changing the edit controls. The problem was somewhat inconsistent, which made it even harder to cope with.

I have no problems using my Dell monitors with DVI, but using an Apple mini display port / thunderbolt port to Dell DVI doesn't work on any of mine (I don't have the 30") because the Dell just says "Not Supported", yet those adapters with with my other monitors.

I've currently got a pair of Dell U3014 30" monitors that I use in a few different combinations... I also have a pair of Apple 24" LED Cinema Displays. I use them in different combos with my Mac Pro, 13" MacBook Pro, Mac Mini or Sony VAIO Duo 11.

The Mac Pro was originally set up using dual video cards so I could run the dual LED cinema displays. The only connection option on the Apple LED Cinema Displays is the (m)DisplayPort and the video card options for the Mac Pro were VERY slim at the time.

My MacBook Pro has the first generation (m)DisplayPort, so I've run one of the Apple LED's hooked up to it when I travel.

The MacMini currently has one of the Dell 30's and I while I would prefer to run them dual, the MacMini's video just won't handle both Dell 30's at full resolution. It runs one at full resolution (2560x1600) connected via (m)DisplayPort absolutely fantastic. It will actually run both Dell 30's in full resolution, mirrored, doing the daisy chain connection method, but with no option to turn off the display mirroring. Hooking up one via (m)DisplayPort and the other via HDMI results in one monitor at full resolution and the other "dumbed" down, however any display method can be selected. Thunderbolt has opened up some interesting options, an external GPU connected via Thunderbolt on the MacMini (or MacBook Pro) is something I would like to play around with...

Sorry for the ramble of random information... The short answer is: I'm very happy with the Dell 30's hooked up anything I've had plugged into them.